- Optics1
- Order of the Golden Fleece1
- Orders of knighthood and chivalry1
- Ordinatio (Duns Scotus, John)1
- Oviedo family1
- Oviedo, Francisco de, 1728-1
- Oviedo, Gregorio de, 1721-17961
- Oviedo, Nicolás de, 1725-1
- Painted leather bindings1
- Papal documents1
- Passion plays1
- Patrick, Saint, 373?-463?1
- Paul, the Hermit, Saint, -approximately 3411
- Peace of Westphalia (1648)1
- Penmanship, German1
- Persian language--Foreign words and phrases--Arabic1
- Persian letters1
- Persian prose literature1
- Persian scripts1
- Personal correspondence1